The MaGui Bagua Promotion Centre.
This is the worldwide, umbrella organization, headed by Li Baohua. The website is in Chinese, Japanese, and English, and is written by Li himself. Go to the site for lots more information on MaGui baguazhang and Li's seminar schedule.
Membership to the IMBA is US$85 a year (or $60 for NAMGBGA members). Li does not have an online payment system, so if you are not giving him cash, you can send the money via paypal to andrea@maguibagua.org and it will be given to Li.